5 TDB version 2: trivial database library
7 Copyright (C) Andrew Tridgell 1999-2004
8 Copyright (C) Rusty Russell 2010-2011
10 ** NOTE! The following LGPL license applies to the tdb
11 ** library. This does NOT imply that all of Samba is released
14 This library is free software; you can redistribute it and/or
15 modify it under the terms of the GNU Lesser General Public
16 License as published by the Free Software Foundation; either
17 version 3 of the License, or (at your option) any later version.
19 This library is distributed in the hope that it will be useful,
20 but WITHOUT ANY WARRANTY; without even the implied warranty of
21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 Lesser General Public License for more details.
24 You should have received a copy of the GNU Lesser General Public
25 License along with this library; if not, see <http://www.gnu.org/licenses/>.
34 #if HAVE_FILE_OFFSET_BITS
35 #define _FILE_OFFSET_BITS 64
38 #include <sys/types.h>
41 /* For sig_atomic_t. */
50 #include <ccan/compiler/compiler.h>
51 #include <ccan/typesafe_cb/typesafe_cb.h>
52 #include <ccan/cast/cast.h>
58 * tdb_open - open a database file
59 * @name: the file name (can be NULL if flags contains TDB_INTERNAL)
60 * @tdb_flags: options for this database
61 * @open_flags: flags argument for tdb's open() call.
62 * @mode: mode argument for tdb's open() call.
63 * @attributes: linked list of extra attributes for this tdb.
65 * This call opens (and potentially creates) a database file.
66 * Multiple processes can have the TDB file open at once.
68 * On failure it will return NULL, and set errno: it may also call
69 * any log attribute found in @attributes.
74 struct tdb_context *tdb_open(const char *name, int tdb_flags,
75 int open_flags, mode_t mode,
76 union tdb_attribute *attributes);
79 /* flags for tdb_open() */
80 #define TDB_DEFAULT 0 /* just a readability place holder */
81 #define TDB_INTERNAL 2 /* don't store on disk */
82 #define TDB_NOLOCK 4 /* don't do any locking */
83 #define TDB_NOMMAP 8 /* don't use mmap */
84 #define TDB_CONVERT 16 /* convert endian */
85 #define TDB_NOSYNC 64 /* don't use synchronous transactions */
86 #define TDB_SEQNUM 128 /* maintain a sequence number */
87 #define TDB_ALLOW_NESTING 256 /* fake nested transactions */
88 #define TDB_RDONLY 512 /* implied by O_RDONLY */
89 #define TDB_VERSION1 1024 /* create/open an old style TDB */
92 * tdb1_incompatible_hash - better (Jenkins) hash for tdb1
94 * This is better than the default hash for tdb1; but older versions of the
95 * tdb library (prior to version 1.2.6) won't be able to open them.
97 * It only makes sense to specify this (using tdb_attribute_hash) when
98 * creating (with O_CREAT) an old tdb version using TDB_VERSION1. It's
99 * equivalent to the TDB_INCOMPATIBLE_HASH flag for tdb1.
101 uint64_t tdb1_incompatible_hash(const void *, size_t, uint64_t, void *);
104 * tdb_close - close and free a tdb.
105 * @tdb: the tdb context returned from tdb_open()
107 * This always succeeds, in that @tdb is unusable after this call. But if
108 * some unexpected error occurred while closing, it will return non-zero
109 * (the only clue as to cause will be via the log attribute).
111 int tdb_close(struct tdb_context *tdb);
114 * struct tdb_data - representation of keys or values.
115 * @dptr: the data pointer
116 * @dsize: the size of the data pointed to by dptr.
118 * This is the "blob" representation of keys and data used by TDB.
120 typedef struct tdb_data {
126 * enum TDB_ERROR - error returns for TDB
132 TDB_SUCCESS = 0, /* No error. */
133 TDB_ERR_CORRUPT = -1, /* We read the db, and it was bogus. */
134 TDB_ERR_IO = -2, /* We couldn't read/write the db. */
135 TDB_ERR_LOCK = -3, /* Locking failed. */
136 TDB_ERR_OOM = -4, /* Out of Memory. */
137 TDB_ERR_EXISTS = -5, /* The key already exists. */
138 TDB_ERR_NOEXIST = -6, /* The key does not exist. */
139 TDB_ERR_EINVAL = -7, /* You're using it wrong. */
140 TDB_ERR_RDONLY = -8, /* The database is read-only. */
141 TDB_ERR_LAST = TDB_ERR_RDONLY
145 * tdb_store - store a key/value pair in a tdb.
146 * @tdb: the tdb context returned from tdb_open()
148 * @dbuf: the data to associate with the key.
149 * @flag: TDB_REPLACE, TDB_INSERT or TDB_MODIFY.
151 * This inserts (or overwrites) a key/value pair in the TDB. If flag
152 * is TDB_REPLACE, it doesn't matter whether the key exists or not;
153 * TDB_INSERT means it must not exist (returns TDB_ERR_EXISTS otherwise),
154 * and TDB_MODIFY means it must exist (returns TDB_ERR_NOEXIST otherwise).
156 * On success, this returns TDB_SUCCESS.
159 * tdb_fetch, tdb_transaction_start, tdb_append, tdb_delete.
161 enum TDB_ERROR tdb_store(struct tdb_context *tdb,
163 struct tdb_data dbuf,
166 /* flags to tdb_store() */
167 #define TDB_REPLACE 1 /* A readability place holder */
168 #define TDB_INSERT 2 /* Don't overwrite an existing entry */
169 #define TDB_MODIFY 3 /* Don't create an existing entry */
172 * tdb_fetch - fetch a value from a tdb.
173 * @tdb: the tdb context returned from tdb_open()
175 * @data: pointer to data.
177 * This looks up a key in the database and sets it in @data.
179 * If it returns TDB_SUCCESS, the key was found: it is your
180 * responsibility to call free() on @data->dptr.
182 * Otherwise, it returns an error (usually, TDB_ERR_NOEXIST) and @data is
185 enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
186 struct tdb_data *data);
189 * tdb_errorstr - map the tdb error onto a constant readable string
190 * @ecode: the enum TDB_ERROR to map.
192 * This is useful for displaying errors to users.
194 const char *tdb_errorstr(enum TDB_ERROR ecode);
197 * tdb_append - append a value to a key/value pair in a tdb.
198 * @tdb: the tdb context returned from tdb_open()
200 * @dbuf: the data to append.
202 * This is equivalent to fetching a record, reallocating .dptr to add the
203 * data, and writing it back, only it's much more efficient. If the key
204 * doesn't exist, it's equivalent to tdb_store (with an additional hint that
205 * you expect to expand the record in future).
208 * tdb_fetch(), tdb_store()
210 enum TDB_ERROR tdb_append(struct tdb_context *tdb,
211 struct tdb_data key, struct tdb_data dbuf);
214 * tdb_delete - delete a key from a tdb.
215 * @tdb: the tdb context returned from tdb_open()
216 * @key: the key to delete.
218 * Returns TDB_SUCCESS on success, or an error (usually TDB_ERR_NOEXIST).
221 * tdb_fetch(), tdb_store()
223 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key);
226 * tdb_exists - does a key exist in the database?
227 * @tdb: the tdb context returned from tdb_open()
228 * @key: the key to search for.
230 * Returns true if it exists, or false if it doesn't or any other error.
232 bool tdb_exists(struct tdb_context *tdb, TDB_DATA key);
235 * tdb_deq - are struct tdb_data equal?
236 * @a: one struct tdb_data
237 * @b: another struct tdb_data
239 static inline bool tdb_deq(struct tdb_data a, struct tdb_data b)
241 return a.dsize == b.dsize && memcmp(a.dptr, b.dptr, a.dsize) == 0;
245 * tdb_mkdata - make a struct tdb_data from const data
246 * @p: the constant pointer
249 * As the dptr member of struct tdb_data is not constant, you need to
250 * cast it. This function keeps thost casts in one place, as well as
251 * suppressing the warning some compilers give when casting away a
252 * qualifier (eg. gcc with -Wcast-qual)
254 static inline struct tdb_data tdb_mkdata(const void *p, size_t len)
257 d.dptr = cast_const(void *, p);
263 * tdb_transaction_start - start a transaction
264 * @tdb: the tdb context returned from tdb_open()
266 * This begins a series of atomic operations. Other processes will be able
267 * to read the tdb, but not alter it (they will block), nor will they see
268 * any changes until tdb_transaction_commit() is called.
270 * Note that if the TDB_ALLOW_NESTING flag is set, a tdb_transaction_start()
271 * within a transaction will succeed, but it's not a real transaction:
272 * (1) An inner transaction which is committed is not actually committed until
273 * the outer transaction is; if the outer transaction is cancelled, the
274 * inner ones are discarded.
275 * (2) tdb_transaction_cancel() marks the outer transaction as having an error,
276 * so the final tdb_transaction_commit() will fail.
277 * (3) the outer transaction will see the results of the inner transaction.
280 * tdb_transaction_cancel, tdb_transaction_commit.
282 enum TDB_ERROR tdb_transaction_start(struct tdb_context *tdb);
285 * tdb_transaction_cancel - abandon a transaction
286 * @tdb: the tdb context returned from tdb_open()
288 * This aborts a transaction, discarding any changes which were made.
289 * tdb_close() does this implicitly.
291 void tdb_transaction_cancel(struct tdb_context *tdb);
294 * tdb_transaction_commit - commit a transaction
295 * @tdb: the tdb context returned from tdb_open()
297 * This completes a transaction, writing any changes which were made.
299 * fsync() is used to commit the transaction (unless TDB_NOSYNC is set),
300 * making it robust against machine crashes, but very slow compared to
301 * other TDB operations.
303 * A failure can only be caused by unexpected errors (eg. I/O or
304 * memory); this is no point looping on transaction failure.
307 * tdb_transaction_prepare_commit()
309 enum TDB_ERROR tdb_transaction_commit(struct tdb_context *tdb);
312 * tdb_transaction_prepare_commit - prepare to commit a transaction
313 * @tdb: the tdb context returned from tdb_open()
315 * This ensures we have the resources to commit a transaction (using
316 * tdb_transaction_commit): if this succeeds then a transaction will only
317 * fail if the write() or fsync() calls fail.
319 * If this fails you must still call tdb_transaction_cancel() to cancel
323 * tdb_transaction_commit()
325 enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb);
328 * tdb_traverse - traverse a TDB
329 * @tdb: the tdb context returned from tdb_open()
330 * @fn: the function to call for every key/value pair (or NULL)
331 * @p: the pointer to hand to @f
333 * This walks the TDB until all they keys have been traversed, or @fn
334 * returns non-zero. If the traverse function or other processes are
335 * changing data or adding or deleting keys, the traverse may be
336 * unreliable: keys may be skipped or (rarely) visited twice.
338 * There is one specific exception: the special case of deleting the
339 * current key does not undermine the reliability of the traversal.
341 * On success, returns the number of keys iterated. On error returns
342 * a negative enum TDB_ERROR value.
344 #define tdb_traverse(tdb, fn, p) \
345 tdb_traverse_(tdb, typesafe_cb_preargs(int, void *, (fn), (p), \
346 struct tdb_context *, \
347 TDB_DATA, TDB_DATA), (p))
349 int64_t tdb_traverse_(struct tdb_context *tdb,
350 int (*fn)(struct tdb_context *,
351 TDB_DATA, TDB_DATA, void *), void *p);
354 * tdb_parse_record - operate directly on data in the database.
355 * @tdb: the tdb context returned from tdb_open()
356 * @key: the key whose record we should hand to @parse
357 * @parse: the function to call for the data
358 * @data: the private pointer to hand to @parse (types must match).
360 * This avoids a copy for many cases, by handing you a pointer into
361 * the memory-mapped database. It also locks the record to prevent
362 * other accesses at the same time.
364 * Do not alter the data handed to parse()!
366 #define tdb_parse_record(tdb, key, parse, data) \
367 tdb_parse_record_((tdb), (key), \
368 typesafe_cb_preargs(enum TDB_ERROR, void *, \
370 TDB_DATA, TDB_DATA), (data))
372 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
374 enum TDB_ERROR (*parse)(TDB_DATA k,
380 * tdb_get_seqnum - get a database sequence number
381 * @tdb: the tdb context returned from tdb_open()
383 * This returns a sequence number: any change to the database from a
384 * tdb context opened with the TDB_SEQNUM flag will cause that number
385 * to increment. Note that the incrementing is unreliable (it is done
386 * without locking), so this is only useful as an optimization.
388 * For example, you may have a regular database backup routine which
389 * does not operate if the sequence number is unchanged. In the
390 * unlikely event of a failed increment, it will be backed up next
393 * Returns an enum TDB_ERROR (ie. negative) on error.
395 int64_t tdb_get_seqnum(struct tdb_context *tdb);
398 * tdb_firstkey - get the "first" key in a TDB
399 * @tdb: the tdb context returned from tdb_open()
400 * @key: pointer to key.
402 * This returns an arbitrary key in the database; with tdb_nextkey() it allows
403 * open-coded traversal of the database, though it is slightly less efficient
406 * It is your responsibility to free @key->dptr on success.
408 * Returns TDB_ERR_NOEXIST if the database is empty.
410 enum TDB_ERROR tdb_firstkey(struct tdb_context *tdb, struct tdb_data *key);
413 * tdb_nextkey - get the "next" key in a TDB
414 * @tdb: the tdb context returned from tdb_open()
415 * @key: a key returned by tdb_firstkey() or tdb_nextkey().
417 * This returns another key in the database; it will free @key.dptr for
420 * Returns TDB_ERR_NOEXIST if there are no more keys.
422 enum TDB_ERROR tdb_nextkey(struct tdb_context *tdb, struct tdb_data *key);
425 * tdb_chainlock - lock a record in the TDB
426 * @tdb: the tdb context returned from tdb_open()
427 * @key: the key to lock.
429 * This prevents any access occurring to a group of keys including @key,
430 * even if @key does not exist. This allows primitive atomic updates of
431 * records without using transactions.
433 * You cannot begin a transaction while holding a tdb_chainlock(), nor can
434 * you do any operations on any other keys in the database. This also means
435 * that you cannot hold more than one tdb_chainlock() at a time.
440 enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
443 * tdb_chainunlock - unlock a record in the TDB
444 * @tdb: the tdb context returned from tdb_open()
445 * @key: the key to unlock.
447 * The key must have previously been locked by tdb_chainlock().
449 void tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
452 * tdb_chainlock_read - lock a record in the TDB, for reading
453 * @tdb: the tdb context returned from tdb_open()
454 * @key: the key to lock.
456 * This prevents any changes from occurring to a group of keys including @key,
457 * even if @key does not exist. This allows primitive atomic updates of
458 * records without using transactions.
460 * You cannot begin a transaction while holding a tdb_chainlock_read(), nor can
461 * you do any operations on any other keys in the database. This also means
462 * that you cannot hold more than one tdb_chainlock()/read() at a time.
467 enum TDB_ERROR tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key);
470 * tdb_chainunlock_read - unlock a record in the TDB for reading
471 * @tdb: the tdb context returned from tdb_open()
472 * @key: the key to unlock.
474 * The key must have previously been locked by tdb_chainlock_read().
476 void tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key);
479 * tdb_lockall - lock the entire TDB
480 * @tdb: the tdb context returned from tdb_open()
482 * You cannot hold a tdb_chainlock while calling this. It nests, so you
483 * must call tdb_unlockall as many times as you call tdb_lockall.
485 enum TDB_ERROR tdb_lockall(struct tdb_context *tdb);
488 * tdb_unlockall - unlock the entire TDB
489 * @tdb: the tdb context returned from tdb_open()
491 void tdb_unlockall(struct tdb_context *tdb);
494 * tdb_lockall_read - lock the entire TDB for reading
495 * @tdb: the tdb context returned from tdb_open()
497 * This prevents others writing to the database, eg. tdb_delete, tdb_store,
498 * tdb_append, but not tdb_fetch.
500 * You cannot hold a tdb_chainlock while calling this. It nests, so you
501 * must call tdb_unlockall_read as many times as you call tdb_lockall_read.
503 enum TDB_ERROR tdb_lockall_read(struct tdb_context *tdb);
506 * tdb_unlockall_read - unlock the entire TDB for reading
507 * @tdb: the tdb context returned from tdb_open()
509 void tdb_unlockall_read(struct tdb_context *tdb);
512 * tdb_wipe_all - wipe the database clean
513 * @tdb: the tdb context returned from tdb_open()
515 * Completely erase the database. This is faster than iterating through
516 * each key and doing tdb_delete.
518 enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb);
521 * tdb_repack - repack the database
522 * @tdb: the tdb context returned from tdb_open()
524 * This repacks the database; if it is suffering from a great deal of
525 * fragmentation this might help. However, it can take twice the
526 * memory of the existing TDB.
528 enum TDB_ERROR tdb_repack(struct tdb_context *tdb);
531 * tdb_check - check a TDB for consistency
532 * @tdb: the tdb context returned from tdb_open()
533 * @check: function to check each key/data pair (or NULL)
534 * @data: argument for @check, must match type.
536 * This performs a consistency check of the open database, optionally calling
537 * a check() function on each record so you can do your own data consistency
538 * checks as well. If check() returns an error, that is returned from
541 * Returns TDB_SUCCESS or an error.
543 #define tdb_check(tdb, check, data) \
544 tdb_check_((tdb), typesafe_cb_preargs(enum TDB_ERROR, void *, \
550 enum TDB_ERROR tdb_check_(struct tdb_context *tdb,
551 enum TDB_ERROR (*check)(struct tdb_data k,
557 * tdb_error - get the last error (not threadsafe)
558 * @tdb: the tdb context returned from tdb_open()
560 * Returns the last error returned by a TDB function.
562 * This makes porting from TDB1 easier, but note that the last error is not
563 * reliable in threaded programs.
565 enum TDB_ERROR tdb_error(struct tdb_context *tdb);
568 * enum tdb_summary_flags - flags for tdb_summary.
570 enum tdb_summary_flags {
571 TDB_SUMMARY_HISTOGRAMS = 1 /* Draw graphs in the summary. */
575 * tdb_summary - return a string describing the TDB state
576 * @tdb: the tdb context returned from tdb_open()
577 * @flags: flags to control the summary output.
578 * @summary: pointer to string to allocate.
580 * This returns a developer-readable string describing the overall
581 * state of the tdb, such as the percentage used and sizes of records.
582 * It is designed to provide information about the tdb at a glance
583 * without displaying any keys or data in the database.
585 * On success, sets @summary to point to a malloc()'ed nul-terminated
586 * multi-line string. It is your responsibility to free() it.
588 enum TDB_ERROR tdb_summary(struct tdb_context *tdb,
589 enum tdb_summary_flags flags,
594 * tdb_get_flags - return the flags for a tdb
595 * @tdb: the tdb context returned from tdb_open()
597 * This returns the flags on the current tdb. Some of these are caused by
598 * the flags argument to tdb_open(), others (such as TDB_CONVERT) are
601 unsigned int tdb_get_flags(struct tdb_context *tdb);
604 * tdb_add_flag - set a flag for a tdb
605 * @tdb: the tdb context returned from tdb_open()
606 * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING.
608 * You can use this to set a flag on the TDB. You cannot set these flags
609 * on a TDB_INTERNAL tdb.
611 void tdb_add_flag(struct tdb_context *tdb, unsigned flag);
614 * tdb_remove_flag - unset a flag for a tdb
615 * @tdb: the tdb context returned from tdb_open()
616 * @flag: one of TDB_NOLOCK, TDB_NOMMAP, TDB_NOSYNC or TDB_ALLOW_NESTING.
618 * You can use this to clear a flag on the TDB. You cannot clear flags
619 * on a TDB_INTERNAL tdb.
621 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag);
624 * enum tdb_attribute_type - descriminator for union tdb_attribute.
626 enum tdb_attribute_type {
627 TDB_ATTRIBUTE_LOG = 0,
628 TDB_ATTRIBUTE_HASH = 1,
629 TDB_ATTRIBUTE_SEED = 2,
630 TDB_ATTRIBUTE_STATS = 3,
631 TDB_ATTRIBUTE_OPENHOOK = 4,
632 TDB_ATTRIBUTE_FLOCK = 5,
633 TDB_ATTRIBUTE_TDB1_HASHSIZE = 128,
634 TDB_ATTRIBUTE_TDB1_MAX_DEAD = 129,
638 * tdb_get_attribute - get an attribute for an existing tdb
639 * @tdb: the tdb context returned from tdb_open()
640 * @attr: the union tdb_attribute to set.
642 * This gets an attribute from a TDB which has previously been set (or
643 * may return the default values). Set @attr.base.attr to the
644 * attribute type you want get.
646 enum TDB_ERROR tdb_get_attribute(struct tdb_context *tdb,
647 union tdb_attribute *attr);
650 * tdb_set_attribute - set an attribute for an existing tdb
651 * @tdb: the tdb context returned from tdb_open()
652 * @attr: the union tdb_attribute to set.
654 * This sets an attribute on a TDB, overriding any previous attribute
655 * of the same type. It returns TDB_ERR_EINVAL if the attribute is
656 * unknown or invalid.
658 * Note that TDB_ATTRIBUTE_HASH, TDB_ATTRIBUTE_SEED,
659 * TDB_ATTRIBUTE_OPENHOOK and TDB_ATTRIBUTE_TDB1_HASHSIZE cannot
660 * currently be set after tdb_open.
662 enum TDB_ERROR tdb_set_attribute(struct tdb_context *tdb,
663 const union tdb_attribute *attr);
666 * tdb_unset_attribute - reset an attribute for an existing tdb
667 * @tdb: the tdb context returned from tdb_open()
668 * @type: the attribute type to unset.
670 * This unsets an attribute on a TDB, returning it to the defaults
671 * (where applicable).
673 * Note that it only makes sense for TDB_ATTRIBUTE_LOG and TDB_ATTRIBUTE_FLOCK
676 void tdb_unset_attribute(struct tdb_context *tdb,
677 enum tdb_attribute_type type);
680 * tdb_name - get the name of a tdb
681 * @tdb: the tdb context returned from tdb_open()
683 * This returns a copy of the name string, made at tdb_open() time. If that
684 * argument was NULL (possible for a TDB_INTERNAL db) this will return NULL.
686 * This is mostly useful for logging.
688 const char *tdb_name(const struct tdb_context *tdb);
691 * tdb_fd - get the file descriptor of a tdb
692 * @tdb: the tdb context returned from tdb_open()
694 * This returns the file descriptor for the underlying database file, or -1
697 int tdb_fd(const struct tdb_context *tdb);
700 * tdb_foreach - iterate through every open TDB.
701 * @fn: the function to call for every TDB
702 * @p: the pointer to hand to @fn
704 * TDB internally keeps track of all open TDBs; this function allows you to
705 * iterate through them. If @fn returns non-zero, traversal stops.
707 #define tdb_foreach(fn, p) \
708 tdb_foreach_(typesafe_cb_preargs(int, void *, (fn), (p), \
709 struct tdb_context *), (p))
711 void tdb_foreach_(int (*fn)(struct tdb_context *, void *), void *p);
714 * struct tdb_attribute_base - common fields for all tdb attributes.
716 struct tdb_attribute_base {
717 enum tdb_attribute_type attr;
718 union tdb_attribute *next;
722 * enum tdb_log_level - log levels for tdb_attribute_log
723 * @TDB_LOG_ERROR: used to log unrecoverable errors such as I/O errors
724 * or internal consistency failures.
725 * @TDB_LOG_USE_ERROR: used to log usage errors such as invalid parameters
726 * or writing to a read-only database.
727 * @TDB_LOG_WARNING: used for informational messages on issues which
728 * are unusual but handled by TDB internally, such
729 * as a failure to mmap or failure to open /dev/urandom.
738 * struct tdb_attribute_log - log function attribute
740 * This attribute provides a hook for you to log errors.
742 struct tdb_attribute_log {
743 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_LOG */
744 void (*fn)(struct tdb_context *tdb,
745 enum tdb_log_level level,
746 enum TDB_ERROR ecode,
753 * struct tdb_attribute_hash - hash function attribute
755 * This attribute allows you to provide an alternative hash function.
756 * This hash function will be handed keys from the database; it will also
757 * be handed the 8-byte TDB_HASH_MAGIC value for checking the header (the
758 * tdb_open() will fail if the hash value doesn't match the header).
760 * Note that if your hash function gives different results on
761 * different machine endians, your tdb will no longer work across
762 * different architectures!
764 struct tdb_attribute_hash {
765 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_HASH */
766 uint64_t (*fn)(const void *key, size_t len, uint64_t seed,
772 * struct tdb_attribute_seed - hash function seed attribute
774 * The hash function seed is normally taken from /dev/urandom (or equivalent)
775 * but can be set manually here. This is mainly for testing purposes.
777 struct tdb_attribute_seed {
778 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_SEED */
783 * struct tdb_attribute_stats - tdb operational statistics
785 * This attribute records statistics of various low-level TDB operations.
786 * This can be used to assist performance evaluation. This is only
787 * useful for tdb_get_attribute().
789 * New fields will be added at the end, hence the "size" argument which
790 * indicates how large your structure is: it must be filled in before
791 * calling tdb_get_attribute(), which will overwrite it with the size
794 struct tdb_attribute_stats {
795 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_STATS */
796 size_t size; /* = sizeof(struct tdb_attribute_stats) */
798 uint64_t alloc_subhash;
799 uint64_t alloc_chain;
800 uint64_t alloc_bucket_exact;
801 uint64_t alloc_bucket_max;
802 uint64_t alloc_leftover;
803 uint64_t alloc_coalesce_tried;
804 uint64_t alloc_coalesce_iterate_clash;
805 uint64_t alloc_coalesce_lockfail;
806 uint64_t alloc_coalesce_race;
807 uint64_t alloc_coalesce_succeeded;
808 uint64_t alloc_coalesce_num_merged;
810 uint64_t compare_wrong_bucket;
811 uint64_t compare_wrong_offsetbits;
812 uint64_t compare_wrong_keylen;
813 uint64_t compare_wrong_rechash;
814 uint64_t compare_wrong_keycmp;
815 uint64_t transactions;
816 uint64_t transaction_cancel;
817 uint64_t transaction_nest;
818 uint64_t transaction_expand_file;
819 uint64_t transaction_read_direct;
820 uint64_t transaction_read_direct_fail;
821 uint64_t transaction_write_direct;
822 uint64_t transaction_write_direct_fail;
826 uint64_t lock_lowlevel;
827 uint64_t lock_nonblock;
828 uint64_t lock_nonblock_fail;
832 * struct tdb_attribute_openhook - tdb special effects hook for open
834 * This attribute contains a function to call once we have the OPEN_LOCK
835 * for the tdb, but before we've examined its contents. If this succeeds,
836 * the tdb will be populated if it's then zero-length.
838 * This is a hack to allow support for TDB1-style TDB_CLEAR_IF_FIRST
841 struct tdb_attribute_openhook {
842 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_OPENHOOK */
843 enum TDB_ERROR (*fn)(int fd, void *data);
848 * struct tdb_attribute_flock - tdb special effects hook for file locking
850 * This attribute contains function to call to place locks on a file; it can
851 * be used to support non-blocking operations or lock proxying.
853 * They should return 0 on success, -1 on failure and set errno.
855 * An error will be logged on error if errno is neither EAGAIN nor EINTR
856 * (normally it would only return EAGAIN if waitflag is false, and
857 * loop internally on EINTR).
859 struct tdb_attribute_flock {
860 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_FLOCK */
861 int (*lock)(int fd,int rw, off_t off, off_t len, bool waitflag, void *);
862 int (*unlock)(int fd, int rw, off_t off, off_t len, void *);
867 * struct tdb_attribute_tdb1_hashsize - tdb1 hashsize
869 * This attribute allows setting the TDB1 hashsize; it only makes sense with
870 * O_CREAT and TDB_VERSION1.
872 * Hashsize should generally be a prime, such as 10007.
874 struct tdb_attribute_tdb1_hashsize {
875 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_TDB1_HASHSIZE */
880 * struct tdb_attribute_tdb1_max_dead - tdb1 number of maximum dead records.
882 * TDB1 has a method to speed up its slow free list: it lets a certain
883 * number of "dead" records build up before freeing them. This is
884 * particularly useful for volatile TDBs; setting it to 5 is
885 * equivalent to tdb1's TDB_VOLATILE flag.
887 struct tdb_attribute_tdb1_max_dead {
888 struct tdb_attribute_base base; /* .attr = TDB_ATTRIBUTE_TDB1_MAX_DEAD */
889 unsigned int max_dead;
893 * union tdb_attribute - tdb attributes.
895 * This represents all the known attributes.
898 * struct tdb_attribute_log, struct tdb_attribute_hash,
899 * struct tdb_attribute_seed, struct tdb_attribute_stats,
900 * struct tdb_attribute_openhook, struct tdb_attribute_flock.
902 union tdb_attribute {
903 struct tdb_attribute_base base;
904 struct tdb_attribute_log log;
905 struct tdb_attribute_hash hash;
906 struct tdb_attribute_seed seed;
907 struct tdb_attribute_stats stats;
908 struct tdb_attribute_openhook openhook;
909 struct tdb_attribute_flock flock;
910 struct tdb_attribute_tdb1_hashsize tdb1_hashsize;
911 struct tdb_attribute_tdb1_max_dead tdb1_max_dead;